Accompanied by a collage of FBI officers at work, Mr Comey wrote: "'I want the American people to know this truth: The FBI is honest. The FBI is strong. And the FBI is, and always will be, independent.' Me (8 June 2017)."

“I want the American people to know this truth: The FBI is honest. The FBI is strong. And the FBI is, and always will be, independent.”Me (June 8, 2017) pic.twitter.com/OZ1ZiBrMNL

His response follows Mr Trump facing claims he obstructed justice after appearing to confirm he knew Flynn lied to the FBI over conversations with Russia's ambassador to the US.

Responding to allegations he attempted to pressure Mr Comey "to let Flynn go" after learning the retired general made false statements to agents, Mr Trump said he "never asked Comey to stop investigating Flynn".

In his tweets, the President said it was a case of "fake news covering another Comey lie".

The President wrote: "After years of Comey, with the phony and dishonest Clinton investigation (and more), running the FBI, its reputation is in tatters – worst in history! But fear not, we will bring it back to greatness."

On Saturday, the President tweeted that he had fired Flynn "because he lied to the Vice President and the FBI". However, at the time of the dismissal, the White House had only acknowledged that Flynn had lied to VP Mike Pence.

Sources close to Mr Trump distanced the President from his tweet describing why he sacked Flynn, saying it was "crafted" by John Dowd, one his personal lawyers.

Image:Michael Flynn pleaded guilty to making false statements to the FBI

Mr Dowd told the Reuters news agency he drafted the tweet but said putting it together had been a "mistake" after Flynn pleaded guilty to making false statements to the FBI.

Some legal experts have said if Mr Trump knew if Flynn lied to the FBI and then pressured Mr Comey not to investigate him, it could lead to an obstruction of justice charge.

The top Democrat on the Senate Judiciary Committee, senator Dianne Feinstein, said the billionaire businessman's "continual tweets" pointed to an obstruction of justice case.

Image:Mr Trump has said there was 'no collusion' between his campaign team and Russia

She told NBC's Meet the Press: "I see it most importantly in what happened with the firing of director Comey. And it is my belief that that is directly because he did not agree to lift the cloud of the Russia investigation. That's obstruction of justice."

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Flynn was the first member of the President's administration to plead guilty to a crime uncovered in a probe into Russian attempts to influence last year's election.

Russia has denied being involved in the election and Mr Trump has said there was no collusion.